diff --git a/mcp/src/gitree/__tests__/jarvis-node-key.test.ts b/mcp/src/gitree/__tests__/jarvis-node-key.test.ts
new file mode 100644
index 000000000..58c3a0b2a
--- /dev/null
+++ b/mcp/src/gitree/__tests__/jarvis-node-key.test.ts
@@ -0,0 +1,58 @@
+/**
+ * Unit tests for jarvisConceptNodeKey.
+ *
+ * The function must reproduce jarvis's sanitize_node_key + _compose_node_key
+ * (jarvis api/helper/schema_validation.py) byte-for-byte: the value is
+ * matched by equality in jarvis's MERGE and covered by a
+ * (node_key, namespace) uniqueness constraint, so any divergence either
+ * re-forks duplicates or throws on write. The expected values below marked
+ * "prod" are actual node_key values jarvis assigned on a production graph.
+ */
+import { test, expect } from "../../testkit.js";
+import { jarvisConceptNodeKey } from "../store/utils.js";
+
+test.describe("jarvisConceptNodeKey", () => {
+  test("matches jarvis-assigned keys from prod (punctuation, ampersand, hyphens)", () => {
+    // prod: jarvis wrote these exact keys for these exact names
+    expect(
+      jarvisConceptNodeKey("Change-of-Control & Anti-Assignment Provision Analysis")
+    ).toBe("concept-changeofcontrolantiassignmentprovisionanalysis");
+    expect(jarvisConceptNodeKey("treaty-silence-as-non-concurrency")).toBe(
+      "concept-treatysilenceasnonconcurrency"
+    );
+    expect(jarvisConceptNodeKey("PLI: Return on Sales (ROS)")).toBe(
+      "concept-plireturnonsalesros"
+    );
+  });
+
+  test("strips spaces before lowercasing and drops unicode punctuation", () => {
+    expect(jarvisConceptNodeKey("  Working Capital Pegs, Collars — True-Up  ")).toBe(
+      "concept-workingcapitalpegscollarstrueup"
+    );
+  });
+
+  test("keeps digits", () => {
+    expect(jarvisConceptNodeKey("Section 382 Ownership Change")).toBe(
+      "concept-section382ownershipchange"
+    );
+  });
+
+  test("preserves non-space whitespace like jarvis does", () => {
+    // jarvis removes only " " (str.replace) before stripping to
+    // [a-zA-Z0-9\s] — a tab survives both steps. Bug-compatible on purpose.
+    expect(jarvisConceptNodeKey("a\tb")).toBe("concept-a\tb");
+  });
+
+  test("hashes the value portion past 200 chars", () => {
+    const name = "x".repeat(250);
+    const key = jarvisConceptNodeKey(name);
+    // hashlib.sha256(("x"*250).encode()).hexdigest()[:32], per _compose_node_key
+    expect(key).toBe("concept-086d4a1c293bde318dc1fec9a21b9d82");
+    expect(key.length).toBe(40);
+  });
+
+  test("does not hash at exactly 200 chars", () => {
+    const name = "y".repeat(192); // "concept-" + 192 = 200
+    expect(jarvisConceptNodeKey(name)).toBe(`concept-${"y".repeat(192)}`);
+  });
+});
diff --git a/mcp/src/gitree/store/graphStorage.ts b/mcp/src/gitree/store/graphStorage.ts
index 51ee642a7..ff239a427 100644
--- a/mcp/src/gitree/store/graphStorage.ts
+++ b/mcp/src/gitree/store/graphStorage.ts
@@ -14,7 +14,7 @@ import {
   ChronologicalCheckpoint,
   Usage,
 } from "../types.js";
-import { formatPRMarkdown, formatCommitMarkdown, parseRepoFromUrl, computeConceptEmbedding, conceptEmbeddingText } from "./utils.js";
+import { formatPRMarkdown, formatCommitMarkdown, parseRepoFromUrl, computeConceptEmbedding, conceptEmbeddingText, jarvisConceptNodeKey } from "./utils.js";
 import { addUsage, normalizeUsage } from "../../aieo/src/usage.js";
 import { jarvisRedisEnabled, pushJarvisEmbeddingJob } from "./jarvis.js";
 
@@ -667,6 +667,47 @@ export class GraphStorage extends Storage {
         }
       );
 
+      // Stamp jarvis's identity onto the node: its create-or-merge resolves
+      // Concepts by MERGE (node:Concept:Node {node_key, namespace}), not by
+      // our id slug, so without these a jarvis-side write of the same
+      // concept forks a duplicate. Kept out of the MERGE above and made
+      // best-effort deliberately: node_key carries a (node_key, namespace)
+      // uniqueness constraint, and a rename that computes an already-taken
+      // key must not fail the content save. The NOT EXISTS guards skip the
+      // stamp when another node holds the key (leaving the old node_key in
+      // place, so the node stays jarvis-addressable under its prior name);
+      // a lost race with a concurrent writer throws on the constraint and
+      // is caught the same way.
+      try {
+        const nodeKey = jarvisConceptNodeKey(concept.name);
+        const keyResult = await session.run(
+          `
+          MATCH (f:Concept {id: $id})
+          WHERE NOT EXISTS {
+              MATCH (o:Node {node_key: $nodeKey, namespace: $namespace})
+              WHERE o <> f
+            }
+            AND NOT EXISTS {
+              MATCH (o:Concept {node_key: $nodeKey, namespace: $namespace})
+              WHERE o <> f
+            }
+          SET f:Node, f.node_key = $nodeKey
+          RETURN f
+          `,
+          { id: concept.id, nodeKey, namespace: "default" }
+        );
+        if (keyResult.records.length === 0) {
+          console.warn(
+            `Concept ${concept.id}: node_key '${nodeKey}' is held by another node — left unstamped (jarvis writes to this name will target that node)`
+          );
+        }
+      } catch (error) {
+        console.warn(
+          `Concept ${concept.id}: failed to stamp jarvis node_key:`,
+          error
+        );
+      }
+
       // jarvis's vector search reads text_embeddings, which only its Redis
       // embedding worker writes — queue a job so this concept shows up there.
       const savedRefId =
diff --git a/mcp/src/gitree/store/utils.ts b/mcp/src/gitree/store/utils.ts
index 3cccf6980..36d5047da 100644
--- a/mcp/src/gitree/store/utils.ts
+++ b/mcp/src/gitree/store/utils.ts
@@ -1,3 +1,4 @@
+import { createHash } from "crypto";
 import { Concept, PRRecord, CommitRecord } from "../types.js";
 import { Storage } from "./index.js";
 
@@ -101,6 +102,36 @@ export function generateSlug(name: string): string {
     .replace(/^-|-$/g, "");
 }
 
+/**
+ * Compute the node_key jarvis would assign this Concept.
+ *
+ * Jarvis's create-or-merge resolves nodes by
+ * `MERGE (node:Concept:Node {node_key, namespace})` — never by our `id`
+ * slug — so a Concept written here without a node_key is invisible to it,
+ * and any jarvis-side write of the "same" concept forks a duplicate node.
+ * Stamping the key (and the :Node label) at save time gives both writers
+ * one identity.
+ *
+ * This must reproduce jarvis's `sanitize_node_key` + `_compose_node_key`
+ * (api/helper/schema_validation.py) byte-for-byte, since the value is
+ * matched by equality and covered by a (node_key, namespace) uniqueness
+ * constraint. Its steps for the `concept-name` key: trim, remove spaces,
+ * lowercase, strip anything outside [a-zA-Z0-9\s], prefix "concept-";
+ * past 200 chars the value portion is replaced by the first 32 hex chars
+ * of its sha256. Verified against 670 jarvis-written keys in prod.
+ */
+export function jarvisConceptNodeKey(name: string): string {
+  const value = name
+    .trim()
+    .replace(/ /g, "")
+    .toLowerCase()
+    .replace(/[^a-zA-Z0-9\s]/g, "");
+  const composed = `concept-${value}`;
+  if (composed.length <= 200) return composed;
+  const digest = createHash("sha256").update(value, "utf-8").digest("hex");
+  return `concept-${digest.slice(0, 32)}`;
+}
+
 /**
  * Format PR as markdown
  */